Information recording method, information recording device, and recording medium containing a program, with recording marks formed by emitting light

ABSTRACT

A first trial write process obtains an optimum recording power of a test pattern even with respect to data having different rules for the recording waveforms corresponding n type data length sets, and a second trial write process using this optimum recording power obtains optimum pulse width or optimum pulse edge position separately for each data length set. Based on the optimum recording power and optimum recording waveform obtained by these trial write processes, recording operation is performed so as to form all the data lengths with satisfactory accuracy, thereby making it possible to obtain a proper reproduced signal.

FIELD OF THE INVENTION

The present invention relates to an information recording method,information recording apparatus, and record medium having a programembodied therein for use with respect to various recording media such asCD-R, CD-RW, DVD-R, DVD-RW, DVD-RAM, and DVD+RW.

BACKGROUND TECHNOLOGY

In recent years, recordable optical disk drive apparatuses such as CD-Rdrive apparatus have been put into practical use, and further study hasbeen made with the aim of achieving further increase in the storagecapacity and recording speed. Recordable optical disk media includeswrite-once optical disks using dye media, rewritable disks usingmagneto-optical media, phase-change media, or the like.

Typical optical disk recording apparatus uses a semiconductor laser as alight source, and emits on a record medium the laser light that ispulse-modulated in response to record information, thereby formingrecord marks. In doing so, the state of the formed record mark changesin response to the power of the recording laser light, so that there isa need to know a recording power that is suitable to the characteristicsof the recording medium. To this end, conventionally, trial write isperformed with respect to a predetermined area (PCA: power calibrationarea) as preparation for the start of recording while the recordingpower is changed. After the trial write, the area that produces thereproduced signal having the most satisfactory quality is identified,and the power that was used to record this area is identified as theoptimum recording power. This method is known as an OPC (optimum powercontol) method. During the actual recording of data, the optimumrecording power identified in this manner is maintained while recording.

As a recording method used for optical disks such as CD and DVD, a markedge recording method is employed in which the length of marks suitablefor high-density recording carries information. In order to reproducedata correctly, there is a need for accurate control of mark shape andedge position. Further, for the purpose of organizing the mark shapeevenly regardless of the length of the marks, a multi-pulse recordingmethod is widely used that forms recording marks by use of pulse trainsthat are divided into a plurality of recording pulses. This method formsa long mark evenly by forming and connecting marks through therepetition of heating and cooling cycles. Such method is also employedin the write-once dye-type media.

DISCLOSURE OF THE INVENTION

[Problem to be Solved by the Invention]

In response to the recent demand for faster recording, various recordingmethods have been proposed, one of which is to lower the frequency ofrecording waveforms. When the frequency of a reference clock signalincreases with an increase in the recording speed, for example, the timelength of heating and cooling of the multi-pulse recording becomesextremely short. The limit to the rising time and falling time of the LDlight emission waveform thus causes the light emission pulses to be lesssharp, resulting in a sufficient heating time and cooling time failingto be secured. A recording failure thus occurs. In consideration ofthis, instead of increasing the number of multi-pulses with each clockcycle in accordance with the data length, a pair of a heating pulse anda cooling pulse may be increased on a two-clock-cycle basis. This is 2Tstrategy method, which is generalized as an nT strategy method by whicha pair of a heating pulse and a cooling pulse is increased on ann-clock-cycle basis (n is an integer that is 2 or larger). These methodshave been put into practical use.

The relationship between the nT strategy method and the recording pulsewaveform is as follows. A deviation Δ from the ideal value of arecording mark length with respect to a recording power Pw shifts fromone data length set to another data length set as the data lengths areclassified by the remainder of the division of each data length by aninteger n. Because of this, pulse width and pulse edge position areselected separately for each data length set. A recommended value iscomputed based on the results of evaluation obtained by use of a testerin advance.

FIG. 11( a) illustrates an example of a histogram of each mark datalength with respect to a satisfactorily reproduced signal. Theconfiguration of the recording pulses is based on the 2T strategy. Anaverage of each data length set (3, 5, 7, 9, 11T) that corresponds tothe remainder “1” of the division by n=2, i.e., having an odd-numberlength, and an average of each data length set (4, 6, 8, 10, 14T) thatcorresponds to the remainder “0” of the division by n=2, i.e., having aneven-number length, need to be distributed at equal intervals. In thecase of DVD-type disks, the mark length is 3T to 14T (T is the cycle ofthe data reference clock), but 14T is omitted in FIG. 11. Here, anaverage of each data length set having an even-number data length mayhave a deviation ±Δ from the ideal value when the optimum recordingpower is used. Namely, when the rules of recording waveforms differbetween the odd-number-length data length set and the even-number-lengthdata length set, a difference from the odd-number-length data length setmay develop, depending on whether each pulse width and pulse edgeposition match the recording power. As a result, only when the optimumrecording power identified by the trial write is optimally combined witheach pulse width and pulse edge position of the even-number-length datalength set and the odd-number-length data length set, the mark lengthbecomes the ideal length as shown in FIG. 11( a).

In an example shown in FIG. 11( b), the recording power may be small, orthe pulse width and pulse edge position may be shifted such that anaverage length of an even-number-length data length set becomes shorterthan the ideal length. In an example shown in FIG. 11( c), the recordingpower may be large, or the pulse width and pulse edge position may beshifted such that an average length of an even-number-length data lengthset becomes longer than the ideal length.

As described above, in the 2T strategy recording method for conventionalhigh-speed recording, or more generally, in the nT strategy recordingmethod that uses a recording pulse train, the trial write (OPC) isperformed to compute an optimum recording power. In so doing, theoptimum recording power is obtained by performing the trial write withchanges in the recording power while maintaining constant pulse widthand pulse edge position regardless of the recording power.

In such OPC method as described above, however, the relationship betweenthe recording power and the deviation from the data-length-specificideal value depends on the conditions of rapid cooling by thearrangement of heating pulses and cooling pulses, and, thus, variesbetween the even-number-length data length set and the odd-number-lengthdata length set. When a different optimum recording power is computedfrom the combination of the preset recording power and the pulse widthand pulse edge position preset in the pre-format information of thedisk, a deviation of the mark length from the above-noted ideal valueincreases. More specifically, if there is variation in the record mediumand/or the recording apparatus (i.g., variation of the recording pulsewaveform due to the variation of the LD driving unit), the relationshipbetween the optimum recording power Po (optimum) and the pulse width andpulse edge position of the recording pulses also varies. Because ofthis, the precision of mark shape and mark position is undermined todegrade performance, which gives rise to a problem by serving as afactor to cause data error.

It is an object of the present invention to achieve accurate recordingby obtaining optimum pulse width and pulse edge position in a recordingmethod that performs recording according to the rules of recordingwaveform using different pulse widths and pulse edge positions forindividual data length sets with respect to the data length sets havingthe different relationship between the number of multi-pulsesconstituting a recording pulse train and the data length.

Further, there is a need to set the pulse width and pulse edge positionseparately for each data length set because the relationship between thenT strategy method and the recording pulse waveform is such that therelationship between the deviation Δ from the ideal value of a recordingmark length and the recording power Pw shifts from one data length setto another data length set as the data lengths are classified by theremainder of the division of each data length by an integer n.

Another object of the present invention is to achieve proper recordingby use of an optimum recording power computed from trial write such thatthe mark length of each even-number-length data length set and eachodd-number-length data length set becomes the ideal length.

[Means for Solving the Problem]

The invention of claim 1 is an information recording method of recordinginformation by forming recording marks by emitting light, from a lightsource on a record medium, modulated according to record information andrules by use of n (n: integer more than one) type data length sets whichare classified by a data length of record information such that therules of recording waveforms thereof are different, including a firsttrial write step of writing as a trial a predetermined first testpattern in a trial write area of the record medium while changing arecording power for emitting in a stepwise manner, so as to obtain anoptimum recording power from a reproduced signal of recorded trial writedata, and a second trial write step of performing trial write in thetrial write area of the record medium by use of the optimum recordingpower by using a second test pattern corresponding to each of the datalength sets while changing pulse width or pulse edge position ofrecording waveform for each of the data length sets in a stepwisemanner, and obtaining an optimum pulse width or optimum pulse edgeposition of the recording waveform corresponding to each of the datalength sets from a reproduced signal of each recorded second testpattern, wherein information is recorded based on the optimum recordingpower obtained in said first trial write step and the optimum pulsewidth or optimum pulse edge position obtained in the second trial writestep.

The invention of claim 2 is the information recording method as claimedin claim 1, wherein said first trial write step includes a first testpattern generating step of generating the first test pattern forperforming trial write in the trial write area of the record medium, andan optimum recording power obtaining step of obtaining the optimumrecording power from the reproduced signal of the recorded trial writedata, and wherein said second trial write step includes a second testpattern generating step of generating the second test patterncorresponding to each of the data length sets for performing of trialwrite, a trial write processing step of performing trial write in thetrial write area of the record medium by using the optimum recordingpower and the second test pattern while maintaining fixed pulse widthand fixed pulse edge position of recording waveform for one or moreparticular data length sets and while changing pulse width or pulse edgeposition of recording waveform for other data length sets in a stepwisemanner, and an optimum recording waveform obtaining step of obtainingthe optimum pulse width or optimum pulse edge position of recordingwaveform corresponding to the data length sets from the reproducedsignal of the second test pattern corresponding to said other datalength sets by using a reference asymmetry value derived from areproduced signal of recorded trial write data corresponding to thesecond test pattern corresponding to said one or more particular datasets.

The invention of claim 3 is the information recording method as claimedin claim 1 or 2, wherein the first test pattern is a data seriesincluding all data lengths, and wherein the second test pattern has apredetermined data length, and is a data series that constitutes the ntype data length sets.

The invention of claim 4 is the information recording method as claimedin claim 1 or 3, wherein the optimum recording power in said first trialwrite step is obtained from a modulation factor of the reproduced signalof the area in which trial write is performed in said step, or obtainedfrom a rate of change in the modulation factor, and wherein the optimumpulse width or optimum pulse edge position corresponding to each of thedata length sets in said second trial write step is obtained from anasymmetry that is a ratio of a positive-side peak value to anegative-side peak value relative to an average value level of thereproduced signal of the area in which trial write is performed in saidstep.

The invention of claim 5 is the information recording method as claimedin claim 2 or 3, wherein the optimum recording power in said first trialwrite step is obtained such that a modulation factor, or a rate ofchange in the modulation factor, of the reproduced signal of the area inwhich trial write is performed in said step becomes a desired value, andwherein the optimum pulse width or optimum pulse edge positioncorresponding to each of said other data length sets in said secondtrial write step is obtained such that an asymmetry of the reproducedsignal of the area in which trial write is performed in said stepsubstantially coincides with a value of an asymmetry corresponding tosaid one or more particular data length sets.

The invention of claim 6 is the information recording method as claimedin claim 5, wherein the optimum pulse width or optimum pulse edgeposition corresponding to each of the data length sets in said secondtrial write step is obtained from an average value of the reproducedsignal corresponding to each of the n type data length sets in the areain which trial write is performed in said step.

The invention of claim 7 is an information recording method of recordinginformation by forming recording marks by emitting light, from a lightsource on a record medium, modulated according to record information andrules by use of n (n: integer more than one) type data length sets whichare classified by a data length of record information such that therules of recording waveforms thereof are different, including a trialwrite step, provided separately for each of the data length sets, ofperforming trial write in a trial write area of the record medium by useof the optimum recording power by using a test pattern corresponding toeach of the data length sets while changing pulse width or pulse edgeposition of recording waveform for each of the data length sets in astepwise manner, and obtaining an optimum pulse width or optimum pulseedge position of the recording waveform corresponding to each of thedata length sets from a reproduced signal of each recorded second testpattern, wherein information is recorded based on the optimum pulsewidth or optimum pulse edge position obtained in each trial write step.

The invention of claim 8 is the information recording method as claimedin any one of claims 1 through 7, wherein the data length sets areclassified according to a remainder of division of the data length ofthe record information by the integer n, and the data length sets have,as a data length corresponding to a clock cycle T of the recordinformation, a rule by which a pair of a heating pulse and a coolingpulse is added for each nT multi-pulses constituting the record waveformof the n type data length sets.

The invention of claim 9 is the information recording method as claimedin claim 2 or 5, wherein the integer n is 2, and a pair of a heatingpulse and a cooling pulse is added for every 2T multi-pulsesconstituting the record waveform of each of the data length sets, andwherein the data length sets having odd-number-length data lengths withrespect to a clock cycle T of the record information are used as saidparticular data length sets.

The invention of claim 10 is an information recording apparatus forrecording information by forming recording marks by emitting light, froma light source on a record medium, modulated according to recordinformation and rules by use of n (n: integer more than one) type datalength sets which are classified by a data length of record informationsuch that the rules of recording waveforms thereof are different,including a first trial write unit to write as a trial a predeterminedfirst test pattern in a trial write area of the record medium whilechanging a recording power for emitting in a stepwise manner, so as toobtain an optimum recording power from a reproduced signal of recordedtrial write data, and a second trial write unit to perform trial writein the trial write area of the record medium by use of the optimumrecording power by using a second test pattern corresponding to each ofthe data length sets while changing pulse width or pulse edge positionof recording waveform for each of the data length sets in a stepwisemanner, and obtaining an optimum pulse width or optimum pulse edgeposition of the recording waveform corresponding to each of the datalength sets from a reproduced signal of each recorded second testpattern, wherein information is recorded based on the optimum recordingpower obtained by said first trial write unit and the optimum pulsewidth or optimum pulse edge position obtained by the second trial writeunit.

The invention of claim 11 is the information recording apparatus asclaimed in claim 10, wherein said first trial write unit includes afirst test pattern generating unit to generate the first test patternfor performing trial write in the trial write area of the record medium,and an optimum recording power obtaining unit to obtain the optimumrecording power from the reproduced signal of the recorded trial writedata, and wherein said second trial write unit includes a second testpattern generating unit to generate the second test patterncorresponding to each of the data length sets for performing of trialwrite, a trial write processing unit to perform trial write in the trialwrite area of the record medium by using the optimum recording power andthe second test pattern while maintaining fixed pulse width and fixedpulse edge position of recording waveform for one or more particulardata length sets and while changing pulse width or pulse edge positionof recording waveform for other data length sets in a stepwise manner,and an optimum recording waveform obtaining unit to obtain the optimumpulse width or optimum pulse edge position of recording waveformcorresponding to the data length sets from the reproduced signal of thesecond test pattern corresponding to said other data length sets byusing a reference asymmetry value derived from a reproduced signal ofrecorded trial write data corresponding to the second test patterncorresponding to said one or more particular data sets.

The invention of claim 12 is the information recording apparatus asclaimed in claim 10 or 11, wherein the first test pattern is a dataseries including all data lengths, and wherein the second test patternhas a predetermined data length, and is a data series that constitutesthe n type data length sets.

The invention of claim 13 is the information recording method as claimedin claim 10 or 12, wherein the optimum recording power in said firsttrial write unit is obtained from a modulation factor of the reproducedsignal of the area in which trial write is performed in said unit, orobtained from a rate of change in the modulation factor, and wherein theoptimum pulse width or optimum pulse edge position corresponding to eachof the data length sets in said second trial write unit is obtained froman asymmetry that is a ratio of a positive-side peak value to anegative-side peak value relative to an average value level of thereproduced signal of the area in which trial write is performed in saidunit.

The invention of claim 14 is the information recording apparatus asclaimed in claim 11 or 12, wherein the optimum recording power in saidfirst trial write unit is obtained such that a modulation factor, or arate of change in the modulation factor, of the reproduced signal of thearea in which trial write is performed in said unit becomes a desiredvalue, and wherein the optimum pulse width or optimum pulse edgeposition corresponding to each of said other data length sets in saidsecond trial write unit is obtained such that an asymmetry of thereproduced signal of the area in which trial write is performed in saidunit substantially coincides with a value of an asymmetry correspondingto said one or more particular data length sets.

The invention of claim 15 is the information recording apparatus asclaimed in apparatus 14, wherein the optimum pulse width or optimumpulse edge position corresponding to each of the data length sets insaid second trial write unit is obtained from an average value of thereproduced signal corresponding to each of the n type data length setsin the area in which trial write is performed in said unit.

The invention of claim 16 is an information recording apparatus forrecording information by forming recording marks by emitting light, froma light source on a record medium, modulated according to recordinformation and rules by use of n (n: integer more than one) type datalength sets which are classified by a data length of record informationsuch that the rules of recording waveforms thereof are different,including a trial write unit, provided separately for each of the datalength sets, to perform trial write in a trial write area of the recordmedium by use of the optimum recording power by using a test patterncorresponding to each of the data length sets while changing pulse widthor pulse edge position of recording waveform for each of the data lengthsets in a stepwise manner, and to obtain an optimum pulse width oroptimum pulse edge position of the recording waveform corresponding toeach of the data length sets from a reproduced signal of each recordedsecond test pattern, wherein information is recorded based on theoptimum pulse width or optimum pulse edge position obtained by eachtrial write unit.

The invention of claim 17 is the information recording apparatus asclaimed in any one of claims 10 through 16, wherein the data length setsare classified according to a remainder of division of the data lengthof the record information by the integer n, and the data length setshave, as a data length corresponding to a clock cycle T of the recordinformation, a rule by which a pair of a heating pulse and a coolingpulse is added for each nT multi-pulses constituting the record waveformof the n type data length sets.

The invention of claim 18 is the information recording apparatus asclaimed in claim 11 or 14, wherein the integer n is 2, and a pair of aheating pulse and a cooling pulse is added for every 2T multi-pulsesconstituting the record waveform of each of the data length sets, andwherein the data length sets having odd-number-length data lengths withrespect to a clock cycle T of the record information are used as saidparticular data length sets.

The invention of claim 19 is a record medium having an informationrecording program recorded therein for causing a controller to recordinformation by forming recording marks by emitting light, from a lightsource on a record medium, modulated according to record information andrules by use of n (n: integer more than one) type data length sets whichare classified by a data length of record information such that therules of recording waveforms thereof are different, said informationrecording program causing said controller to perform a first trial writestep of writing as a trial a predetermined first test pattern in a trialwrite area of the record medium while changing a recording power foremitting in a stepwise manner, so as to obtain an optimum recordingpower from a reproduced signal of recorded trial write data, and asecond trial write step of performing trial write in the trial writearea of the record medium by use of the optimum recording power by usinga second test pattern corresponding to each of the data length setswhile changing pulse width or pulse edge position of recording waveformfor each of the data length sets in a stepwise manner, and obtaining anoptimum pulse width or optimum pulse edge position of the recordingwaveform corresponding to each of the data length sets from a reproducedsignal of each recorded second test pattern, wherein said controller iscaused by said information recording program to record information basedon the optimum recording power obtained in said first trial write stepand the optimum pulse width or optimum pulse edge position obtained inthe second trial write step.

The invention of claim 20 is the record medium having the informationrecording program recorded therein as claimed in claim 19, wherein saidfirst trial write step of said information recording program causes saidcontroller to perform a first test pattern generating step of generatingthe first test pattern for performing trial write in the trial writearea of the record medium, and an optimum recording power obtaining stepof obtaining the optimum recording power from the reproduced signal ofthe recorded trial write data, and wherein said second trial write stepof said information recording program causes said controller to perform,a second test pattern generating step of generating the second testpattern corresponding to each of the data length sets for performing oftrial write, a trial write processing step of performing trial write inthe trial write area of the record medium by using the optimum recordingpower and the second test pattern while maintaining fixed pulse widthand fixed pulse edge position of recording waveform for one or moreparticular data length sets and while changing pulse width or pulse edgeposition of recording waveform for other data length sets in a stepwisemanner, and an optimum recording waveform obtaining step of obtainingthe optimum pulse width or optimum pulse edge position of recordingwaveform corresponding to the data length sets from the reproducedsignal of the second test pattern corresponding to said other datalength sets by using a reference asymmetry value derived from areproduced signal of recorded trial write data corresponding to thesecond test pattern corresponding to said one or more particular datasets.

[Advantage of the Invention]

According to the invention claimed in claim 1, 2, 10, 11, 19, or 20, anoptimum recording power of a test pattern is obtained even with respectto data having rules for the recording waveforms corresponding n typedata length sets, and the trial write using this optimum recording powerobtains optimum pulse width or optimum pulse edge position separatelyfor each data length set. Based on the optimum power and recordingwaveform, therefore, recording operation is performed so as to form allthe data lengths with satisfactory accuracy, thereby producing a properreproduced signal.

According to the invention claimed in claim 3 or 12, the second testpattern is a data series constituting a plurality of data length sets,so that it is possible to achieve the trial write that matches therecording waveform corresponding to each data length set. Since there isno error in the detected values of the reproduced signal, optimum pulsewidth or pulse edge position can be obtained accurately.

According to the invention claimed in claim 4 or 13, the first trialwrite process can produce the optimum recording power easily withsatisfactory precision. Further, a difference in the data length of eachdata length set can be easily detected with satisfactory precision. Itis thus possible to perform proper recording that is superior in termsof matching between the recording power and the pulse width or pulseedge position.

According to the invention claimed in claims 5 through 7 and 14 through16, with respect to the n type data length sets and each test pattern, atrial write process is performed separately for each data length set soas to obtain the pulse width or pulse edge position of each optimumrecording waveform such as to allow a detected value of a separatereproduced signal to be obtained. It is thus possible to perform properrecording that is superior in terms of matching between the recordingpower and the pulse width or pulse edge position.

According to the invention claimed in claims 8, 9, 17, and 18, themethod that uses recording waveforms having the number of multi-pulsesreduced, as is often referred to as the nT strategy, which is used inthe high-speed recording of a phase-change-type disk, and the so-called2T strategy that is adoptable to the high-speed recording of CD or DVD,make it possible to achieve proper recording on such recording mediumwithout creating a disparity in the recording pulse width or pulse edgeposition and the optimum recording power between the odd-number-lengthdata length sets and the even-number-length data length sets.

[Advantage of the Invention]

According to the present invention, it is possible to achieve accuraterecording by obtaining each optimum pulse width and pulse edge positionin a recording method that performs recording according to the rules ofrecording waveform using different pulse widths and pulse edge positionsfor individual data length sets with respect to the data length setshaving the different relationship between the number of multi-pulsesconstituting a recording pulse train and the data length.

Further, according to the present invention, it is possible to achieveproper recording by use of an optimum recording power computed fromtrial write such that the mark length of each even-number-length datalength set and each odd-number-length data length set becomes the ideallength.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a block diagram showing an example of the outlineconfiguration of an optical information recording apparatus according toan embodiment of the present invention.

FIG. 1B is an outline functional block diagram of an informationrecording program stored in a record medium.

FIG. 2 is an illustrative drawing regarding a PCA area and a trial writemethod.

FIG. 3 is a drawing showing an I diagram of a reproduced signal.

FIG. 4 is a waveform diagram showing an example of light emissionrecording waveform used in the 2T strategy with respect to each recordinformation item.

FIG. 5 is a waveform diagram showing an enlarged view of a selectedportion thereof.

FIG. 6 is a drawing showing the way the average value characteristics ofa reproduced signal differ depending on the data length set.

FIG. 7 is an outline flowchart showing an example of trial write processcontrol.

FIG. 8 is a flowchart showing further details.

FIG. 9A is an illustrative drawing relating to various examples ofsettings of pulse edge position and pulse width.

FIG. 9B is an illustrative drawing relating to various examples ofsettings of pulse edge position and pulse width.

FIG. 9C is an illustrative drawing relating to various examples ofsettings of pulse edge position and pulse width.

FIG. 9D is an illustrative drawing relating to various examples ofsettings of pulse edge position and pulse width.

FIG. 10 is an outline flowchart showing an example of trial writeprocess control according to another embodiment.

FIG. 11 is a drawing showing a histogram with respect to each mark datalength of a reproduced signal.

DESCRIPTION OF SYMBOLS

-   1 Record Medium-   2 Trial Write Area

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of the present invention will be described with referenceto the accompanying drawings. An information recording apparatus of thisembodiment is an example of application to an optical informationrecording apparatus. FIG. 1A is a block diagram showing an example ofthe outline configuration of such optical information recordingapparatus.

A record medium 1 used in this optical information recording apparatusis a recordable record medium (e.g., optical disks such as CD-R, CD-RW,DVD-R, DVD-RW, DVD+R, DVD+RW, DVD-RAM, MD, and MO). A spindle motor 2for revolving the record medium 1 is controlled to achieve a constantlinear velocity (CLV) or a constant angular velocity (CAV) according tothe signals supplied from a servo controller 3. An optical pickup (PU) 4shines the light emitted from a semiconductor laser (LD) on the recordmedium 1 to perform information writing, or receives reflective lightreturning from the record medium 1 for conversion into a received-lightsignal. The optical pickup 4 includes the light source, a lightreceiving device for receiving the reflective light for conversion intothe received-light signal, an optical system, an actuator, and so on.The optical pickup 4 is further provided with a monitor light receivingunit for monitoring a portion of the light emitted from the lightsource. The output monitor signal is used to control the variation ofthe intensity of the light emitted from the light source. Further, atilt detecting light receiving unit may be provided in some cases forthe purpose of detecting a tilt of the record medium 1 relative to theemitted light.

A received light signal processing unit 5 receives received-lightsignals from various light receiving units provided in the opticalpickup 4, an performs various signal processing. A reproduced signal Srfis obtained from the received-light signal. Together with the servocontroller 3, an actuator is driven and controlled (focus-servo controland track-servo control) such that the light is always shone within apredetermined error range against variation such as surface wobblesassociated with the rotation of the record medium 1 and the deviation ofthe track in the radial direction. To this end, a servo-error signal Ssvis generated from the received-light signal, and is supplied to theservo controller 3. The optical pickup 4 is movable in the radialdirection of the record medium 1, and performs a seek operation such asto emit the light spot at a desired position. The servo controller 3also serves to perform the seek control, the rotation control of therecord medium 1, the tilt control, etc., according to the addressinformation and the like prerecorded on the record medium 1.

A wobble of a record track winding at predetermined frequency is formedin advance on the record medium 1. The received light signal processingunit 5 also generates a wobble signal Swbl made by extracting the wobblecomponent. Based on the wobble signal Swbl, a wobble signal processingunit 6 performs rotation control, detection of address information,generation of a recording clock WCK serving as a reference clock at thetime of recording.

A reproduced signal processing unit 7 demodulates the reproduced signalSrf according to the predetermined modulation scheme rules of the recordmedium 1 that is being reproduced. Further, the reproduced signalprocessing unit 7 extracts a reproduced clock by use of a built-in PLLcircuit. The demodulated data is supplied to a controller 8.

An encoder 9 modulates record information supplied from the controller 8according to the predetermined modulation scheme rules, thereby togenerate record data. In so doing, the generation of the record data isbased on the recording clock WCK serving as a reference. In DVDrecording apparatus, for example, the EFM+ modulation method isemployed, and the pulse length of record data Wdata is 3T to 11T, and14T (T is the cycle of the recording clock WCK).

An LD driving unit 10 modulates the light source LD with a predeterminedlight waveform according to the record data Wdata and the recordingclock WCK. The emitting power and light waveform information are set bythe controller 8. Further, a monitor received-light signal is suppliedfrom the received light signal processing unit 5. Based on the monitorreceived-light signal, control (so-called APC (automatic power control))is performed such that the amount of the light emitted from the lightsource LD becomes a desired value.

The controller 8 executes a firmware program (F/W program) stored in aflash ROM 13 to perform an information recording/reproducing methodaccording to the present invention, and performs the function of eachmeans of the optical information recording apparatus according to thepresent invention.

The flash ROM 13 is a nonvolatile memory, which can be erased orrewritten by the controller 8. The flash ROM 13 stores therein programsfor the overall control of the optical information recording apparatusand firmware programs comprised of an information recording program 15for performing the steps of the information recording/reproducing methodaccording to the present invention.

As shown in FIG. 1B, the information recording program 15 is configuredsuch as to cause the controller 8 to perform a first trial write meansand a second trial write means. The first trial write means includes afirst test pattern generating means and an optimum recording powercomputing means, and the second trial write means includes a second testpattern generating means, a trial write processing means, and an optimumrecording waveform computing means.

The information recording program 15 can be distributed by being storedin a record medium 16. The record medium 16 is a record medium thatrecords information optically, electrically, or magnetically, and may bean optical disk such as CD or DVD, a memory card comprised of a flashmemory, a flexible disk, a magneto-optical disk (MO), an IC memory, orthe like. The record medium 16 can be anything as long as it can recordinformation.

The record medium 16 is mounted on the optical information recordingapparatus or in the memory card reader or the like of a main computer(so-called personal computer or DVD player) coupled to the opticalinformation recording apparatus. The information recording program 15 isthen installed into the flash ROM 13. The information recording program15 may alternatively be downloaded and installed through a network.

The record medium 1 has a PCA (power calibration area=trial write area)21 in a predetermined region (e.g., the innermost portion) as shown inFIG. 2( a). Prior to the start of the intended recording, trial write isperformed with respect to this area to obtain an optimum recordingpower. At the time of actual recording, OPC (optimum power control) isperformed such that recording is carried out by use of the obtainedoptimum recording power. As shown in FIG. 2( b), further, a single trialwrite is performed by use of one ECC block (one ECC block includes 16sectors) serving as a unit of information recording, for example, andthe recording power is changed on a sector-by-sector basis.

Consequently, the reproduced signal Srf from the area in which the trialwrite is performed becomes as shown in FIG. 2( c). An OPC detecting unit11 then detects a maximum value Ipk, a minimum value Ibt, and an averagevalue (DC value) Idc with respect to each sector of the reproducedsignals Srf. FIG. 3 is an example of the I diagram of the reproducessignal Srf. The controller 8 performs reproduction with respect to thearea in which trial write is performed, and detects these values,followed by computing an optimum recording power from these values byperforming a predetermined computation. This computation will later bedescribed in detail.

A test signal generating unit 12 generates trial write data (testpattern) at the time of performing trial write. The trial write data issupplied to the encoder 9. At the time of trial write, this data isselectively output for provision to the LD driving unit 10.

The controller 8 performs the functions previously described, processingcontrol as will be described, and the exchange of record/reproducedinformation and command communication with the host computer (notshown). In this manner, the overall control of the apparatus isachieved.

FIG. 4 shows an example of the waveform of the light emitted from thelight source LD when a phase-change-type record medium (rewritablerecord medium) such as a DVD-RW is used as the record medium 1. FIG. 4(a) illustrates the recording clock WCK, FIG. 4( b) illustrating therecord data Wdata, and FIG. 4( c) illustrating the waveform of opticalrecording in the case of the data length of the record data Wdata being3T(1) through 14T(10). The emitting power is set such that a bottompower is Pb, an erase power being Pe, and a write power being Pw.

When the frequency of the recording clock reaches a speed exceeding 100MHz such as in the case of 24× write/read CD-RW or faster, 5× write/readDVD-RW or faster, or the like, the waveform of the emitted light showsless defined edges because the rise time and fall time of the lightsource LD are about 1.5 ns. The waveform of the emitted light is thusnot a rectangular wave, failing to secure a sufficient heating time andcooling time. In consideration of this, the 2T strategy that uses thesame number of pulses for 4T and 5T, for 6T and 7T, for 8T and 9T, andfor 10T and 11T, respectively, is employed to achieve high-speedrecording.

More specifically, the odd-number data length sets (3, 5, 7, 9, 11T) asshown in FIG. 5( b) and the even-number data length sets (4, 6, 8, 10,14T) as shown in FIG. 5( c) have different rules for the pulse width andpulse edge position of recording waveforms. Here, an example of 9T andan example of 10T are shown. The leading edge positions Tsfpo and Tsfpeof the first heating pulse, the leading edge positions Tsmpo and Tsmpeof the first heating multi-pulse in the multi-pulse portion, and theleading edge positions Tslpo and Tslpe of the last heating pulse are setdifferently between the odd-number-length data length set and theeven-number-length data length set (“e” at the end indicates an oddnumber, and “o” indicates an even number).

The width Tfp, Tmp, or Tlp of each heating pulse and the width Tecp ofthe last cooling pulse substantially coincide between theodd-number-length data length set and the even-number-length data lengthset. For the purpose of trial write as will be described, the pulsewidth Tlpo and Tlpe of the last heating pulse and the pulse width Tecpomand Tecpe of the last cooling pulse are settable to different widths.

Example of settings will be shown in the following.

-   -   Tsfpo=1.1T, Tsfpe=1.0T    -   Tsmpo=1.6T, Tsmpe=1.0T    -   Tslpo=2.1T, Tslpe=1.0T    -   Tecpo=Tecpe=0.2T    -   Tfpo=Tfpe=Tmpo=Tmpe=Tlpo=Tlpe=0.8T

In general, the write power of each data length set is the samerecording power Pw (=Pwo=Pwe) The predetermined pulse width and pulseedge position settings are determined based on combinations with theoptimum recording power Po by the testing performed at the time of diskmanufacturing.

The optical information recording apparatus has a different spotdiameter and different light emission time due to variation of theoptical system or variation of the LD driving unit 10. There is thus adeviation from the optimum recording power that is computed based on thetrial write by the optical information recording apparatus. Because ofthis, if the initial settings of pulse width and pulse edge position ofeach odd-number-length data length set and even-number-length datalength set are used without any change, a deviation (edge shift) occursto deviate from the ideal length of the data length set with respect tothe computed optimum recording power. In this embodiment, thus, anadditional step is provided as a special feature to correct the settingsof either one of the data length sets.

In the trial write process of a special feature of the presentembodiment as will later be described, according to the combinationsbetween the record medium 1 and the information recording apparatus,there is a need to correct a deviation as shown in the histogram havinga decreased average because of the shortened formation of aneven-number-length data length as shown in FIG. 11( b) or as shown inthe histogram having an increased average because of the lengthenedformation of an even-number-length data length as shown in FIG. 11( b).To this end, the pulse edge position or pulse width of the recordingwaveform for creating an even-number-length mark is corrected aspreviously described. This makes it possible to form a mark as shown inFIG. 11( a) in which the odd-number-length data length and theeven-number-length data length coincide with sufficient precision withthe ideal lengths obtained by using the recording clock cycle T as areference.

With reference to flowcharts of FIG. 7 and FIG. 8, a description will begiven of an example of process control of the information recordingmethod suitable to the record medium 1, which is performed by thecontroller 8 implemented by use of a microcomputer. FIG. 8 is aflowchart showing the finer details of the process example than FIG. 7.These will be described in parallel.

FIG. 7 is a flowchart showing an algorithm for computing pulse width andpulse edge position with respect to each data length set and the optimumrecording power Pw(opt). The computation of the optimum recording poweris performed as a preparation prior to the start of recordinginformation. Schematically, such computation includes a first trialwrite step and first trial write means of computing the optimumrecording power Pw(opt), and a second trial write step and second trialwrite means of computing correction values for the pulse width or thepulse edge position based on the computed optimum recording powerPw(opt).

At step S1 (S11), a first test pattern to be used in the first trialwrite process is generated (first test pattern generating step, firsttest pattern generating means). The first test pattern is comprised ofall data patterns, and is supposed to meet the predetermined modulationrules. In the first trial write process, the first test pattern issupplied from the encoder 9 as the record data Wdata.

At step S2 (S12), while the recording power Pw (Pw1, Pw2, Pw3, Pw4, . .. ) is changed by a predetermined step size on a sector-by-sector basis,the first test pattern is recorded in the predetermined trial write areaof the record medium 1.

In step S3 (S13), the area in which the trial write is performed at stepS2 is reproduced, and the power that is used to record the sector forwhich the reproduced signal Srf is most satisfactory is identified asthe optimum recording power Pw(opt) Steps S2 and S3 (S12 and S13) areperformed as the first test pattern generating process and the firsttest pattern generating means.

In order to evaluate the quality of the reproduced signal, an example asshown below may be used.

Firstly, the maximum value Ipk, the minimum value Ibt, and the averagevalue (DC value) Idc of the reproduced signal Srf are detected withrespect to each sector. Then, the computation:β=[(Ipk−Idc)−(Idc−Ibt)]/(Ipk−Ibt)  (1)is performed separately for each sector, thereby computing asymmetry β.

Typically, the most satisfactory reproduced signal is obtained when β=0,so that the power used for recording the sector closest to zero isproperly identified as the optimum recording power Pw(opt).Alternatively, a formula approximating the recording power Pw and theasymmetry β may be derived, based on which the recording powercorresponding to β=0 may be computed. Such computation is preferable inthe case of a dye-type optical disk.

Secondly, a rate of change in the modulation factor of the reproducedsignal with respect to the recording power may be used as an indication.In the same manner as previously described, the maximum value Ipk andthe minimum value Ibt of the reproduced signal Srf are detected withrespect to each sector. Then, the modulation factor m is computed asfollows.m=(Ipk−Ibt)/Ipk  (2)

Based on the computed modulation factor m and the recording power Pwused at that time, a rate of change γ in the modulation rate m withrespect to the recording power is computed as:γ=(dm/dPw)(Pw/m)  (3)Then, the recording power Pt used when the rate of change γ becomes apredetermined value γt is obtained, and is multiplied by a predeterminedcoefficient k to generate the optimum recording power Pw. Thepredetermined value yt and the coefficient k are determined in advanceseparately for each type of record medium 1 and for each informationrecording apparatus.

A further detailed computing method will be described in the following.Based on a plurality of data sets indicative of the modulation factor mand the recording power Pw detected by reproducing the trial write area,a second-order approximation formula is obtained as:m=a·Pw ² +b·Pw+c  (4) (a, b, c: constants)As a method of approximation, a typical approximation method such aspolynomial approximation may be used. An approximation formula higherthan the second order properly matches the measured samples.

From the formula (3) previously described, dm/dPw=2a·Pw+b is obtained.As a result, a formula (5) as follows is obtained.Pw={−b(γ−1)±SQRT[b ²(γ−1)²−4a(γ−2)cγ]}/2a(γ−2)  (5)Based on these computations, a positive solution Pw+ of the equation (5)is computed to obtain the optimum recording power Pw(opt). Suchcomputation is preferable for a phase-change-type optical disk.

These methods may be combined. Further, a jitter detecting unit may beprovided such as to compute the recording power producing a minimumjitter.

The data length at this time includes all the data lengths, and therecording power deviated from the optimum recording power ends upforming a mark length that differs for each data length set. In thecomputation based on the rate of change γ in the modulation factor,however, the modulation factor is detected based on the relativelylonger data lengths of each data length set. Accordingly, an edge shiftand data-length deviation themselves are not reflected in the computedresults. Namely, even if the computed optimum recording power includesan error due to variation of the information recording apparatus, it isimpossible to detect whether the settings of the pulse width or pulseedge position used in the first trial write process have no displacementbetween the odd-number-length data length sets and theeven-number-length data length sets.

In the present embodiment, in the recording by use of the optimumrecording power, a mark edge shift and/or average data length deviationof each data length set are detected with respect to the data lengthsets for which recording pulse trains are generated according todifferent rules. Then, the pulse width or pulse edge position isadjusted to perform correction.

Further, the trial write may be performed by using the data patternsthat include all the data lengths inclusive of odd-number lengths andeven-number lengths. In such a case, the reproduced signal including anodd-number-length data length and the reproduced signal including aneven-number-length data length may exhibit different values. If thepulse width and pulse edge position of a recording waveform for whichthe optimum recording power is selected in advance are used, theprobability of exhibiting such different values is high, resulting indeviation in the asymmetry of the reproduced signal. By being differentfrom another mark, the reproduced signal Srf from the area that isrecorded by use of the optimum recording power of another mark maybecome as shown in FIG. 6. Namely, the average value Idco including anodd-number-length data length and the average value Idce including aneven-number-length data length are different from each other. Thedetected average value Idc thus includes an error from the average valueIdce including an even-number-length data length. As a result, anerroneous value is computed also for the asymmetry β, resulting in theerroneous computation of an optimum recording power. If the recordingpower and recording waveform are determined under this condition, thehistogram of each data length as shown in FIG. 11( b) and FIG. 11( c)may be obtained. That is, the reproduced signal is such that theodd-number-length and even-number-length data length sets exhibit edgeshifts, which causes degradation in the jitter characteristics,resulting in error in reproduction.

In the present invention embodiment, as shown in the second trial writewhich will be described in the following, a second data pattern for thetrial write purpose is used in order to optimize the pulse width andpulse edge position with respect to. each data length set conforming tothe rules of recording waveform. As a result, the problem as describedabove does not arise, and it is thus possible to compute an optimumrecording power and the pulse width or pulse edge position accurately.

In this method, it is possible to add the shortest data length likely todevelop an edge shift as a separate data length set. A jitter detectingunit for computing an optimum value may be provided so as to compute thepulse width or edge position that achieves the smallest jitter.

The second trial write process having the features as described above isperformed following the first trial write process for computing theoptimum recording power. At step S4 (S14), the second test pattern foruse in the second trial write process is generated (the second testpattern generating process and second test patter generating means). Thesecond test pattern is based on the 2T strategy previously described,and is a data series that constitutes the data length sets (3, 5, 7, 9,11T) having the residual “1” of the division by an integer n=2, i.e., anodd-number-length and the data length sets (4, 6, 8, 10, 14T) having theresidual “0” of the division by n=2, i.e., an even-number-length.

In general, record data such as EFM+ (plus) modulated by the encoder 9has a ratio of the generated quantity differing for each data length. Inthe case of RLL (run length limited code) code as in CD or DVD,generally, a ratio of generated quantity of n-type data patterns afterrandom modulation is equal to 2^(n−1) successively from the shortestdata length. In reality, the data prior to the modulation is assigned toa predetermined data pattern table, so that in the case of EFM+, 3T=32%,4T=25%, 5T=17%, 6T=12%, 7T=7%, 8T=4%, 9T=2%, 10T=1%, 11T<1%, and 14T<1%.Because of this, an average value of the reproduced signal and theasymmetry caused by difference in the data length include errors if theratio of generated quantities differs. Accordingly, the test patternsfor the odd-number-length data length sets and even-number-length datalength sets used in the second trial write process preferably have theratio of generated data quantities as follows: 3T=55%, 5T=30%, 7T=10%,9T=5%, 11T<1% for the odd-number-length data length sets and 4T=58%,6T=28%, 8T=10%, 10T=3%, 14T<1% for the even-number-length data lengthsets. However, patterns that are properly adjusted such as to make anerror ignorable in asymmetry detection are supplied from the controlleras fixed data.

At step S5(S15), the recording power Pw is set to the recording powerPw(opt) computed at step S3, and the second test pattern including onlythe odd-number-length data length sets having the shortest mark lengthin the first sector are recorded. An average value and asymmetry valueof the reproduced signal obtained from this sector are used as referencevalues (S16).

Then, the second test pattern including only the even-number-length datalength sets on a sector-specific basis is used (S17) to bring about alarge change in the pulse width Tfpe or a small change in the leadingpulse edge position Tsfpo of the first heating pulse as previouslydescribed, and also to bring about a large change in the pulse widthTlpe or a large change in the leading pulse edge position Tslpe of thelast heating pulse, thereby causing proper changes at predeterminedintervals such as to make the even-number-length data length relativelylong, while the second test patterns are being recorded in the trialwrite area (S18) (trial write processing process and trial writeprocessing means). Namely, in the case of a phase-change-type diskcomprised of a typical AgInSbTe-type record material, the leading edgeposition of the first heating pulse is shifted forward with respect tothe recording clock, which makes it possible to form the leading edge(start position) of the recording mark such as to achieve a long marklength. At the same time, the leading edge position of the last heatingpulse is shifted backward with respect to the recording clock, whichmakes it possible to form the trailing edge (end position) of therecording mark such as to achieve a long mark length.

In phase-change-type disks, the trial write area may overwrite the firsttrial write area of step S2. Alternatively, the second trial write maybe performed after the erasure. Alternatively, the first trial write maybe performed in the first half of the trial write area (e.g., 1 ECCblock) that can be used in a lump, and the second trial write may beperformed in the second half. In the case of a write-once disk comprisedof a dye or inorganic material for which recording and writing can beperformed only once, the position of pulse edge of recording waveformfor controlling the mark length may have the start position thereofshifted forward or the end position thereof shifted backward, which isthe same as in the case of the phase-change type.

Thereafter, at step S6(S19), the area in which the trial write isperformed at step S5 is reproduced, and the second optimum recordingpulse condition settings Tsfpe(opt), Tfpe(opt), Tslpe(opt), Tlpe(opt),and Tecpe(opt) are computed (optimum recording waveform computingprocess and optimum recording waveform computing means), which are thepulse edge position or pulse width that is used to record the sector forwhich the asymmetry β of the even-number-length reproduced signal Srfmatches the asymmetry value of the odd-number-length reproduced signalserving as a reference value.

In order to evaluate the quality of a reproduced signal, similarly tothe case of the first method of step S3, a maximum value Ipk, minimumvalue Ibt, and average value (DC value) Idc of the reproduced signal Srfare detected with respect to each sector, and the asymmetry β iscomputed by use of the formula (1). The settings of the recording pulseused to record the sector having the asymmetry β close to theodd-number-length reference asymmetry are computed as the optimum pulsesettings (opt). Alternatively, a formula approximating the pulse edgeposition Tsfpe or pulse width Tfpe and the asymmetry β may be derived,based on which the recording power corresponding to β=referenceasymmetry value may be computed. In the second trial write, the pulseedge position or pulse width of the even-number-length data lengths arematching by the recording power obtained in the first trial write. Anodd-number-length average value Idco is the value corresponding to β=0.At step S5(S18), recording is performed while changing the pulse edgeposition or pulse width of the even-number-length recording pulse, sothat an even-number-length average value Idce changes. Accordingly, thesector for which Idc3 becomes the value that satisfies Ipk−Idc3=Idc3−Ibtcorresponds to the asymmetry β=0, and the pulse edge position or pulsewidth Tsfpe(opt), Tfpe(opt), Tslpe(opt), and Tlpe(opt) of the recordingpulse used to record this sector are computed as optimum values (S19).

It should be noted that β=0 is not always the target value of theasymmetry β. The target value may be selected from the range−0.05<β<0.15 that is advantageous in terms of jitter characteristics andrecording margins.

In the following, an example of the settings of the pulse edge and pulsewidth of a recording waveform used in the actual second trial writeprocess will be shown.

In FIG. 9A, the pulse width Tecpe of the last cooling pulse is increasedfrom 0T to 0.6T by increments of 0.1T with respect to theeven-number-length data length sets, while the trial write is performed.When an asymmetry value detected from the reproduced signal coincideswith the reference asymmetry value (=0) obtained from theodd-number-length data length sets, such an asymmetry value isidentified. In this case, the pulse width Tecpe(opt)=0.15T of the lastcooling pulse is obtained as an optimum value.

In FIG. 9B, the leading edge position Tslpe of the last heating pulse isincreased from 0.6T to 1.2T by increments of 0.1T with respect to theeven-number-length data length sets, while the trial write is performed.When an asymmetry value detected from the reproduced signal coincideswith the reference asymmetry value (=0) obtained from theodd-number-length data length sets, such an asymmetry value isidentified. In this case, the leading edge position Tslpe(opt)=0.9T ofthe last heating pulse is obtained as an optimum value.

In FIG. 9C, the pulse width Tlpe of the last heating pulse is increasedfrom 0.4T to 1.0T by increments of 0.1T with respect to theeven-number-length data length sets, while the trial write is performed.When an asymmetry value detected from the reproduced signal coincideswith the reference asymmetry value (=0) obtained from theodd-number-length data length sets, such an asymmetry value isidentified. In this case, the pulse width Tlpe(opt)=0.7T of the lastheating pulse is obtained as an optimum value.

In FIG. 9D, the leading edge position Tsfpe of the first heating pulseis decreased from 1.20T to 0.95T by steps of 0.05T with respect to theeven-number-length data length sets, and, also, the leading edgeposition Tslpe of the last heating pulse is increased from 0.5T to 1.4Tby steps of 0.15T, while the trial write is performed. When an asymmetryvalue detected from the reproduced signal coincides with the referenceasymmetry value (=0) obtained from the odd-number-length data lengthsets, such an asymmetry value is identified. In this case, the leadingedge position Tsfpe(opt)=1.05 of the first heating pulse and the leadingedge position Tslpe(opt)=0.95T of the last heating pulse are obtained asoptimum values.

In this manner, with respect to the data length sets having differentrules regarding recording waveforms, a particular data length set isused as a reference value of a reproduced signal such as to conform tothe disk characteristics and mark formation conditions. The pulse edgeposition and pulse width of recording waveforms for other data lengthsets are effectively selected, and the second trial write allows theoptimum pulse edge position and pulse width to be computed.

As described above, the optimum recording power Pw(opt) is computedthrough the first trial write process, and the optimum pulse conditionsettings Tsfp(opt), Tfp(opt), Tslp(opt), Tlp(opt), Tecp(opt), and thelike are computed through the second trial write process. With this, thetrial write procedure comes to an end.

At the time of normal information recording, the optimum recording powerand optimum pulse condition settings obtained in this manner may be usedto perform recording, which allows all the data lengths to be formedwith sufficient accuracy, thereby achieving precise recording.

When the optimum recording power is computed from the rate of change γin the modulation factor m at step S3, the recording of a relativelyshort mark by use of a power different from the optimum power hardlyaffects the modulation factor m and the rate of change γ. Inconsideration of this, the first test patterns may be comprised of datapatterns (normal data) having all the data lengths, or may be comprisedof particular data patterns having relatively long marks (e.g., noshorter than 6T). The trial write may then be performed while changingthe recording power Pw with respect to the test patterns including thedata length sets serving as a predetermined reference (e.g., odd-numberlength).

In the description provided above, the record medium 1 has beendescribed as a phase-change-type record medium. Even in the case ofanother recording medium such as a dye type or inorganic material type,the OPC method as described above can be properly applied in therecording method that performs recording according to the data lengthsets having different rules regarding recording waveforms.

The first and second test patterns may be formed as a continuous datapattern, so that the trial write for odd-number lengths and the trialwrite for even-number lengths may be performed continuously. After this,these two trial write areas are reproduced at once, and the referenceasymmetry value derived from the odd-number-length data lengths and theoptimum values of pulse edge position or pulse width of the recordingwaveform for the even-number-length data lengths may be computed.Namely, the processes may be performed in the order of steps S11, S12,S13, S14, S15, S17, S18, S16, and S19. With this provision, it ispossible to omit the switching step (such as the time required to accessthe trial write area) between the recording and the reproducing, therebyreducing the trial write process time.

In the following, another embodiment of the information recording methodwill be described with reference to FIG. 10. This embodiment is directedto an example in which n=3. A description will be given of a method inwhich classification by the data length into three data length sets ismade, and an optimum recording power and optimum recording waveform arecomputed with respect to each data length set. More specifically, theso-called 3T strategy, in which classification is made according to theremainders 0, 1, and 2 of the division of a data length by n=3, is used.This information recording method uses a recording waveform in which apair of a heating pulse and a cooling pulse is added each time the datalength increases by 3T. The first data length set has a data length (3,6, 9T) having a remainder of 0, the second data length set with a datalength (4, 7, 10T) having a remainder of 1, and the third data lengthset with a data length (5, 8, 11, 14T) having a remainder of 2. Further,the pulse edge position and pulse width of the recording waveforms usedifferent rules in which suffixes 0, 1, and 2 are added as in Tsfp0,Tsfp1, and Tsfp2. As the recording pulse edge position or pulse width,the pulse edge position Tsfp(0, 1, 2) of the first heating pulse, theedge position Tslp(0, 1, 2) of the last heating pulse, the width Tlp(0,1, 2) of the last heating pulse, the width Tecp(0, 1, 2) of the lastcooling pulse, and so on are combined, and changed while performingtrial write separately for each data length set, thereby computing eachoptimum value.

At step S21, a first test pattern is generated. This first test patternis a random data pattern comprised of all the data lengths.

At step S22, the first test pattern is recorded in the trial write areawhile changing the recording power Pw on a sector-by-sector basis.

At step S23, the area in which the trial write is performed at step S22is reproduced, and the power that is used to record the sector for whichthe reproduced signal Srf is most satisfactory is identified as theoptimum recording power Pw(opt). In order to evaluate the quality of thereproduced signal, the method that uses a rate of change γ in themodulation factor may be employed as in the example previouslydescribed.

At step S24, a second test pattern is generated. This second testpattern is comprised of a test pattern including data lengths of thefirst data length set. Here, a preferable pattern is such that a ratioof generated data lengths is based on a ratio of data modulation.

At step S25, a test pattern comprised of data lengths of the first datalength set including the shortest mark length in the next sector of thetrial write area is recorded by use of the optimum recording powerPw(opt) computed at step S23. Here, a preferable pattern is such that aratio of generated data lengths is based on a ratio of data modulation.

At step S26, the area in which the trial write is performed at step S25is reproduced, and an average value and asymmetry value of thereproduced signal obtained from this sector are set aside as referencevalues. For evaluation of the quality of a reproduced signal, theexample previously described may be employed.

At step S27, the pulse edge position or pulse width (e.g., one of or acombination of Tsfp1, Tslp1, Tslp1, and Tecp1) of recording waveform ischanged for each next sector of the trial write area, while the testpattern comprised of the data lengths of the second data length set isrecorded by using the optimum recording power Pw(opt) computed at stepS23. Here, a preferable pattern is such that a ratio of generated datalengths is based on a ratio of data modulation.

At step S28, the area in which the trial write is performed at step S27is reproduced, and the optimum recording pulse settings Tsfp1(opt),Tfp1(opt), Tslp1(opt), Tlp1(opt), and Tecp1(opt) are computed, which arethe pulse edge position or pulse width that is used to record the sectorfor which the asymmetry β of the reproduced signal Srf of thesecond-data-length-set data lengths matches the asymmetry value of thefirst-data-length-set data lengths serving as a reference value.Alternatively, a formula approximating the pulse edge position or pulsewidth and the asymmetry β may be derived, based on which the recordingpower corresponding to β=reference asymmetry value may be computed. Inthis case also, the example previously described may be adopted in orderto evaluate the quality of a reproduced signal.

At step S29, the pulse edge position or pulse width (e.g., one of or acombination of Tsfp2, Tslp2, Tslp2, and Tecp2) of recording waveform ischanged for each next sector of the trial write area, while the testpattern comprised of the data lengths of the third data length set isrecorded by using the optimum recording power Pw(opt) computed at stepS23. Here, a preferable pattern is such that a ratio of generated datalengths is based on a ratio of data modulation.

At step S30, the area in which the trial write is performed at step S29is reproduced, and the optimum recording pulse settings Tsfp2(opt),Tfp2(opt), Tslp2(opt), Tlp2(opt), and Tecp2(opt) are computed, which arethe pulse edge position or pulse width that is used to record the sectorfor which the asymmetry β of the reproduced signal Srf of thethird-data-length-set data lengths matches the asymmetry value of thefirst-data-length-set data lengths serving as a reference value.Alternatively, a formula approximating the pulse edge position or pulsewidth and the asymmetry β may be derived, based on which the recordingpower corresponding to β=reference asymmetry value may be computed. Inthis case also, the example previously described may be adopted in orderto evaluate the quality of a reproduced signal.

As described above, the optimum recording power Pw(opt) and the optimumvalues of pulse edge position and pulse width for the second and thirddata length sets are computed. With this, the trial write procedurecomes to an end.

At the time of normal information recording, the optimum recording powerand optimum recording waveform obtained in this manner may be used toperform recording, which allows all the data lengths to be formed withsufficient accuracy, thereby achieving precise recording.

In the example described above, a test pattern for each data length setis such that a ratio of generated data lengths of a particular patternfor which the recording power is changed is based on a ratio of datamodulation. Alternatively, patterns that are properly adjusted such asto make an error ignorable in asymmetry detection may be supplied fromthe controller as fixed data.

1. An information recording method of recording information by formingrecording marks by emitting light, from a light source on a recordmedium, modulated according to record information and rules by use of n(n: integer more than one) type data length sets which are classified bya data length of record information such that the rules of recordingwaveforms thereof are different, comprising: a first trial write step ofwriting as a trial a predetermined first test pattern in a trial writearea of the record medium while changing a recording power for emittingin a stepwise manner, so as to obtain an optimum recording power from areproduced signal of recorded trial write data; and a second trial writestep of performing trial write in the trial write area of the recordmedium by use of the optimum recording power by using a second testpattern corresponding to each of the data length sets while changingpulse width or pulse edge position of recording waveform for each of thedata length sets in a stepwise manner, and obtaining an optimum pulsewidth or optimum pulse edge position of the recording waveformcorresponding to each of the data length sets from a reproduced signalof each recorded second test pattern, wherein information is recordedbased on the optimum recording power obtained in said first trial writestep and the optimum pulse width or optimum pulse edge position obtainedin the second trial write step; and wherein said first trial write stepincludes: a first test pattern generating step of generating the firsttest pattern for performing trial write in the trial write area of therecord medium; and an optimum recording power obtaining step ofobtaining the optimum recording power from the reproduced signal of therecorded trial write data, and wherein said second trial write stepincludes: a second test pattern generating step of generating the secondtest pattern corresponding to each of the data length sets forperforming of trial write; a trial write processing step of performingtrial write in the trial write area of the record medium by using theoptimum recording power and the second test pattern while maintainingfixed pulse width and fixed pulse edge position of recording waveformfor one or more particular data length sets and while changing pulsewidth or pulse edge position of recording waveform for other data lengthsets in a stepwise manner; and an optimum recording waveform obtainingstep of obtaining the optimum pulse width or optimum pulse edge positionof recording waveform corresponding to the data length sets from thereproduced signal of the second test pattern corresponding to said otherdata length sets by using a reference asymmetry value derived from areproduced signal of recorded trial write data corresponding to thesecond test pattern corresponding to said one or more particular datasets.
 2. The information recording method as claimed in claim 1, whereinthe first test pattern is a data series including all data lengths, andwherein the second test pattern has a predetermined data length, and isa data series that constitutes the n type data length sets.
 3. Theinformation recording method as claimed in claim 1, wherein the optimumrecording power in said first trial write step is obtained such that amodulation factor, or a rate of change in the modulation factor, of thereproduced signal of the area in which trial write is performed in saidstep becomes a desired value, and wherein the optimum pulse width oroptimum pulse edge position corresponding to each of said other datalength sets in said second trial write step is obtained such that anasymmetry of the reproduced signal of the area in which trial write isperformed in said step substantially coincides with a value of anasymmetry corresponding to said one or more particular data length sets.4. The information recording method as claimed in claim 3, wherein theoptimum pulse width or optimum pulse edge position corresponding to eachof the data length sets in said second trial write step is obtained froman average value of the reproduced signal corresponding to each of the ntype data length sets in the area in which trial write is performed insaid step.
 5. The information recording method as claimed in claim 1 or3, wherein the integer n is 2, and a pair of a heating pulse and acooling pulse is added for every 2T multi-pulses constituting the recordwaveform of each of the data length sets, and wherein the data lengthsets having odd-number-length data lengths with respect to a clock cycleT of the record information are used as said particular data lengthsets.
 6. An information recording method of recording information byforming recording marks by emitting light, from a light source on arecord medium, modulated according to record information and rules byuse of n (n: integer more than one) type data length sets which areclassified by a data length of record information such that the rules ofrecording waveforms thereof are different, comprising: a first trialwrite step of writing as a trial a predetermined first test pattern in atrial write area of the record medium while changing a recording powerfor emitting in a stepwise manner, so as to obtain an optimum recordingpower from a reproduced signal of recorded trial write data; and asecond trial write step of performing trial write in the trial writearea of the record medium by use of the optimum recording power by usinga second test pattern corresponding to each of the data length setswhile changing pulse width or pulse edge position of recording waveformfor each of the data length sets in a stepwise manner, and obtaining anoptimum pulse width or optimum pulse edge position of the recordingwaveform corresponding to each of the data length sets from a reproducedsignal of each recorded second test pattern, wherein information isrecorded based on the optimum recording power obtained in said firsttrial write step and the optimum pulse width or optimum pulse edgeposition obtained in the second trial write step; and wherein theoptimum recording power in said first trial write step is obtained froma modulation factor of the reproduced signal of the area in which trialwrite is performed in said step, or obtained from a rate of change inthe modulation factor, and wherein the optimum pulse width or optimumpulse edge position corresponding to each of the data length sets insaid second trial write step is obtained from an asymmetry that is aratio of a positive-side peak value to a negative-side peak valuerelative to an average value level of the reproduced signal of the areain which trial write is performed in said step.
 7. An informationrecording apparatus for recording information by forming recording marksby emitting light, from a light source on a record medium, modulatedaccording to record information and rules by use of n (n: integer morethan one) type data length sets which are classified by a data length ofrecord information such that the rules of recording waveforms thereofare different, comprising: a first trial write unit to write as a triala predetermined first test pattern in a trial write area of the recordmedium while changing a recording power for emitting in a stepwisemanner, so as to obtain an optimum recording power from a reproducedsignal of recorded trial write data; and a second trial write unit toperform trial write in the trial write area of the record medium by useof the optimum recording power by using a second test patterncorresponding to each of the data length sets while changing pulse widthor pulse edge position of recording waveform for each of the data lengthsets in a stepwise manner, and obtaining an optimum pulse width oroptimum pulse edge position of the recording waveform corresponding toeach of the data length sets from a reproduced signal of each recordedsecond test pattern, wherein information is recorded based on theoptimum recording power obtained by said first trial write unit and theoptimum pulse width or optimum pulse edge position obtained by thesecond trial write unit; and wherein said first trial write unitincludes: a first test pattern generating unit to generate the firsttest pattern for performing trial write in the trial write area of therecord medium; and an optimum recording power obtaining unit to obtainthe optimum recording power from the reproduced signal of the recordedtrial write data, and wherein said second trial write unit includes: asecond test pattern generating unit to generate the second test patterncorresponding to each of the data length sets for performing of trialwrite; a trial write processing unit to perform trial write in the trialwrite area of the record medium by using the optimum recording power andthe second test pattern while maintaining fixed pulse width and fixedpulse edge position of recording waveform for one or more particulardata length sets and while changing pulse width or pulse edge positionof recording waveform for other data length sets in a stepwise manner;and an optimum recording waveform obtaining unit to obtain the optimumpulse width or optimum pulse edge position of recording waveformcorresponding to the data length sets from the reproduced signal of thesecond test pattern corresponding to said other data length sets byusing a reference asymmetry value derived from a reproduced signal ofrecorded trial write data corresponding to the second test patterncorresponding to said one or more particular data sets.
 8. Theinformation recording apparatus as claimed in claim 7, wherein the firsttest pattern is a data series including all data lengths, and whereinthe second test pattern has a predetermined data length, and is a dataseries that constitutes the n type data length sets.
 9. The informationrecording apparatus as claimed in claim 7, wherein the optimum recordingpower in said first trial write unit is obtained such that a modulationfactor, or a rate of change in the modulation factor, of the reproducedsignal of the area in which trial write is performed in said unitbecomes a desired value, and wherein the optimum pulse width or optimumpulse edge position corresponding to each of said other data length setsin said second trial write unit is obtained such that an asymmetry ofthe reproduced signal of the area in which trial write is performed insaid unit substantially coincides with a value of an asymmetrycorresponding to said one or more particular data length sets.
 10. Theinformation recording apparatus as claimed in claim 9, wherein theoptimum pulse width or optimum pulse edge position corresponding to eachof the data length sets in said second trial write unit is obtained froman average value of the reproduced signal corresponding to each of the ntype data length sets in the area in which trial write is performed insaid unit.
 11. The information recording apparatus as claimed in claim 7or 9, wherein the integer n is 2, and a pair of a heating pulse and acooling pulse is added for every 2T multi-pulses constituting the recordwaveform of each of the data length sets, and wherein the data lengthsets having odd-number-length data lengths with respect to a clock cycleT of the record information are used as said particular data lengthsets.
 12. An information recording apparatus for recording informationby forming recording marks by emitting light, from a light source on arecord medium, modulated according to record information and rules byuse of n (n: integer more than one) type data length sets which areclassified by a data length of record information such that the rules ofrecording waveforms thereof are different, comprising: a first trialwrite unit to write as a trial a predetermined first test pattern in atrial write area of the record medium while changing a recording powerfor emitting in a stepwise manner, so as to obtain an optimum recordingpower from a reproduced signal of recorded trial write data; and asecond trial write unit to perform trial write in the trial write areaof the record medium by use of the optimum recording power by using asecond test pattern corresponding to each of the data length sets whilechanging pulse width or pulse edge position of recording waveform foreach of the data length sets in a stepwise manner, and obtaining anoptimum pulse width or optimum pulse edge position of the recordingwaveform corresponding to each of the data length sets from a reproducedsignal of each recorded second test pattern, wherein information isrecorded based on the optimum recording power obtained by said firsttrial write unit and the optimum pulse width or optimum pulse edgeposition obtained by the second trial write unit; and wherein theoptimum recording power in said first trial write unit is obtained froma modulation factor of the reproduced signal of the area in which trialwrite is performed in said unit, or obtained from a rate of change inthe modulation factor, and wherein the optimum pulse width or optimumpulse edge position corresponding to each of the data length sets insaid second trial write unit is obtained from an asymmetry that is aratio of a positive-side peak value to a negative-side peak valuerelative to an average value level of the reproduced signal of the areain which trial write is performed in said unit.
 13. A record mediumhaving an information recording program recorded therein for causing acontroller to record information by forming recording marks by emittinglight, from a light source on a record medium, modulated according torecord information and rules by use of n (n: integer more than one) typedata length sets which are classified by a data length of recordinformation such that the rules of recording waveforms thereof aredifferent, said information recording program causing said controller toperform: a first trial write step of writing as a trial a predeterminedfirst test pattern in a trial write area of the record medium whilechanging a recording power for emitting in a stepwise manner, so as toobtain an optimum recording power from a reproduced signal of recordedtrial write data; and a second trial write step of performing trialwrite in the trial write area of the record medium by use of the optimumrecording power by using a second test pattern corresponding to each ofthe data length sets while changing pulse width or pulse edge positionof recording waveform for each of the data length sets in a stepwisemanner, and obtaining an optimum pulse width or optimum pulse edgeposition of the recording waveform corresponding to each of the datalength sets from a reproduced signal of each recorded second testpattern, wherein said controller is caused by said information recordingprogram to record information based on the optimum recording powerobtained in said first trial write step and the optimum pulse width oroptimum pulse edge position obtained in the second trial write step; andwherein said first trial write step of said information recordingprogram causes said controller to perform: a first test patterngenerating step of generating the first test pattern for performingtrial write in the trial write area of the record medium; and an optimumrecording power obtaining step of obtaining the optimum recording powerfrom the reproduced signal of the recorded trial write data, and whereinsaid second trial write step of said information recording programcauses said controller to perform: a second test pattern generating stepof generating the second test pattern corresponding to each of the datalength sets for performing of trial write; a trial write processing stepof performing trial write in the trial write area of the record mediumby using the optimum recording power and the second test pattern whilemaintaining fixed pulse width and fixed pulse edge position of recordingwaveform for one or more particular data length sets and while changingpulse width or pulse edge position of recording waveform for other datalength sets in a stepwise manner; and an optimum recording waveformobtaining step of obtaining the optimum pulse width or optimum pulseedge position of recording waveform corresponding to the data lengthsets from the reproduced signal of the second test pattern correspondingto said other data length sets by using a reference asymmetry valuederived from a reproduced signal of recorded trial write datacorresponding to the second test pattern corresponding to said one ormore particular data sets.